Induction-meter.



No 808,532. PATENTED DEG.26,1905. A.J.PRAGBR. INDUCTION METER.

APPLICATION FILED OOT. 31,1903.

6 SHEETS-SHEET 1.

No. 808,532. PATENTED D50. 26, 1905. A. J. FRAGER. INDUCTION METER.APPLICATION FILED 0012.31.1903.

8 SHEETS-SHEET 2.

- Twemwif No. 808,532. PATENTED DEC. 26, 1905.

A. J. YPRAGER.

INDUCTION METER.

APPLIOATION FILED oc'r.s1.19os.

6 SHEETS-SHEET 3.

Men/Z07.

No. 808,532. PATENTED DEC. 26, 1905. A. J. FRAGBR.

INDUCTION METER.

APPLICATION FILED 0GT.81.1903.

B SHEETS-SHEET 4.

No. 808,582. PATENTBD DEC. 26, 1905.

A. J. PRAGER.

INDUCTION METER.

APPLICATION FILED OCT. 31.1903.

6 SHEETS-SHBET 5.

PATENTE'D DEC. 26, 1905.

-A. J. FRAGER.

INDUCTION METER.

APPLICATION FILED 00131.1903.

6 SHEETS-SHEET 6.

UNITED STATEB Parana orruon.

ALPHONSE JEAN FRAGER, OF PARIS, FRANCE, ASSIGNQR TO COMPAGNIE POUR LAFABRICATION DES COMPTEURS & MATERIEL DUSINES A GAZ, OF PARIS, FRANCE.

- INDUCTION-METER.

Specification of Letters Patent.

Patented Dec. 26, 1905.

To all whom it nuty concern:

Be it known that I, ALPHoNsE J AN FRAGER, engineer, a citizen of theRepublic of France, residing at 16 Boulevard de Vaugirard, Paris,France, have invented a new and useful Improvement in Induction-Meters,(for which Letters Patent have been applied for in France under date ofFebruary 26, 1903, No. 329,885, and in Germany under date of May 6,1903,) of which the following is a specification.

The present invention has for its object an apparatus of theinduction-meter type in.

which the output is indicated on a series of dials by indexes set inmotion by a drivingshaft which bears adisk or a conductor rotating underthe action of two systems of fluxes, one of which is proportional to thepotential difference of the current to be measured and has a lag equalto an angle a behind this potential difference, while the other isproportional to the volume of said current and has a lead equal to anangle on said current. Special devices allow an adjustment of 01 and sothat they are made complementary. Therefore under these conditions thespeed of the disk is proportional to the energy spent in the circuitirrespective of the phase displacement of current in the latter, and theapparatus constitutes a perfect wattmeter. If the shaft instead ofrotating freely is fixed to a spring acting against its movements, itsangular deflections will give the value of energy by means of an indexmovable on a scale constituting an exact wattmeter, to which allhereinafter-described devices may be applied.

In the accompanying drawings, forming .part of the presentspecification, Figure 1 is a diagram of a three-core transformerindicating the fluxes traversing the same. Fig. 2 shows a mode ofwinding said transformer. Fig. 3 shows a transformer provided with twowindings connected in parallel. Figs. 4 and 5 show two other modes ofwinding, producing no primary flux in one of the cores of thetransformer. Fig. 6 shows the combined action on a disk of a three-coretransformer energized by the current to be measured and a magnetenergized proportionally to the potential difference. Figs. 7 and 8 showthe Fig. 9 is a polar diagram tuted by exterior magnetic shunts.

of the fluxes. Fig. 10 shows another mode of winding a three-coretransformer. Figs. 11 and 12 show the windings corresponding,respectively, to the windings of Figs. 10 and 2, according to amodification in which one of the cores is no longer apparent, but isconsti- Figs. 13 to 19, inclusive, are diagrams illustrating theprinciples of my invention. Figs. 20 to 24 are polar diagrams of thefluxes. Fig. 25 is an elevation of the windingsas used in practice.Figs. 26 and 27 are separate top views of the primary and secondarywindings. Figs. 28 and 29 are an elevation and a top view, respectively,of the general arrangement of windings and connections. Fig. 30 is afront view, and Fig. 31 is a side view, of the complete apparatus.

In putting my invention into practice in order to obtain fluxesproportional to the volume of current I make use of a special device,the principle of which will now be described.

A magnetic circuit is composed, as is the case in threephasetransformers, of three cores, the ends of which are connected togetherby two cross-pieces, the whole being made of laminated iron, Fig. 1. Ifa coil M0, carrying the main current I, be wound on the core X, saidcoil produces in its core an ascending flux Co, which separates into twofluxes C1 and C2, descending through the two other cores. By neglectingthe exterior leakage we obtain C0 C1+C2. These three fluxes are shown infull lines in Fig. 1. If. in like manner a second coil Mr, carrying theauxiliary current L, be wound on the second core Y, this coil producesin its core a descending flux C'1, which in its turn separates into twofluxes U0 and Cz, ascending through the two other cores.

We obtain also (1'1 C2+ Co. Said three fluxes are shown by dotted lines.

Fig. 1 shows the respective directions of the fluxes, supposing that thecurrents I and I1 are in phase. It will be seen that the componentfluxes produced by both currents are similarly directed in the branchesX and Y and oppositely directed in branch Z. If a lag be given tocurrent 11 with respect to current I, the fluxes U0 U1 U2 will assumethe positions indicated diagrammatically in Fig. 9, so that theresulting fluxes 0 1 of cores X Y lag behind Co, While the third branchproduces a resulting flux 2, which leads on flux C2, and consequently oncurrent I.

The case above considered, in which the currents I and I1 act only bymeans of two coils wound on two different cores, is the simplest one;but it is possible to obtain the same result, first, by adding to coilM0 two coils M1 and M2, wound, respectively, on cores Y and Z, traversedby the main current I, and calculated so as to maintain a suitablerelation between the fluxes (10 C1 C2 without changing their direction;second, by adding in the same Way to coil M1 two coils Mz Mo, wound,respectively, on cores X and Z and performing the same function withrespect to fines Oo 0 1 0 2- Two different means may be employed inorder to have the auxiliary current I1 proportional to current I andlagging by a certain angle behind it. The first means consist inshort-circuiting the auxiliary circuit, in which case the main current Iinduces therein a current I1 lagging behind I by the required angle, thethree-core magnetic circuit acting then in the same manner as a truethree-core transformer, Fig. 2. The second means consists in connectingboth electric circuits in parallel by introducing into the generalarrangement of coils a certain amount of asymmetry, which results in acorresponding phase displacement, even if the circuits have the sametime constant. One of the currents I will then lead on the other L onaccount of the mutual induction of both branches, and the same result isobtained as in the first case, Fig. 3.

The above-described device may be used in the construction of awattmeter in causing the flux 2, leading on the current I by an angle toact on a disk together with a shuntflux which lags behind the potentialby an angle An exact wattmeter is obtained by regulating the angles andso that they are complementary, the acting fluxes being then inquadrature. Such a wattmeter is shown in Fig. 6, in which the disk isengaged on the 'one side in an air-gap provided in core B and on theother side in the air-gap of the shuntelectromagnet P; but theindications given by such wattmeters are neither exact nor even constantif small currents have to be meas- "ured by reason of the remanentmagnetism of the iron cores. In my phase displacement device suchdisadvantage is avoided by inserting the core of the current-coil in themagnetic shunt-circuit so that the shunt-flux going from one cross-pieceto the other energiZes continuously said cross-pieces and the threecores from pole to pole, as shown in Fig. 7 but then in order to avoidmutual induction between the shunt-circuit and the main circuit it isnecessary to calculate individually each system of coils M0 M1 M2 and MOM1 M 2, so that there will be no magnetic potential diiference betweenthe two cross-pieces. Figs. 2, 4L, and 5 show three dilferentarrangements of such a system of coils, it being supposed that thereluctances are the same in the three branches.

In Fig. 2

IVL) 2M1 I QIVI O M1 2M5 In Fig. 4

13 10 M1 IVIz I O QIVI O IVIi I IVIOI M1 O MO O F H M 2 In Fig. 5

poles of the shunt-electromagnet two threebranch magnetic circuitsarranged symmetrically, Fig. 8, and the connected lower crosspieces ofwhich close the magnetic circuit of the shunt-current. The main circuitsof said transformers are connected in series, as well as the auxiliarycircuits, so that the electromotive forces induced in the two half partsof the apparatus are equal and opposed.

In an apparatus so constructed the fluxes of the same origin being inphase have no reaction upon each other. The torques due to the actionsbetween primary and secondary circuits are neutralized by reason ofsymmetry, so that the only actions to be taken into account are between"the shunt-flux and the primary and secondary fluxes, respectively. Leta designate the angle of lagging of the shunt-flux behind'the potentialdifference E, and fl the angle of leading of the resulting flux on themain current I. The torque resulting from the several actions is K E Isin, and by regulating a and so that they are complementary said torquebecomes K E I, so that an exact wattmeter for displaced or non-displacedcurrents is obtained.

In the apparatus shown in Fig. 8 I cause only the fluxes of branches Band B to act upon the disk, together with the shunt-flux.

'It is possible by bringing the two transformers nearly together tocause the disk to be acted upon by two other fluxes taken from thetransformers in order to combine their actions with those of the firsttwo. By this action of four branches instead of two branches either areinforcing of the lead or a reinforcing of the torque is obtained,according to whether the four primary fluxes or the four secondaryfluxes have the same direction.

If in the above-described device the two secondary coils are leftindependent instead of being mounted in series, the shunt-flux inducesin said coils a current which tends to give the shunt-fiux an additionallag, while the main fluxes induce currents which tend to give themain-current flux a lead.

In this way two concordant actions are secured, thus more easilyobtaining an exact and strong wattmeter.

Throughout the foregoing I have shown three cores; but nothing will bealtered as to principle and result obtained if one of these cores doesnot really exist and is only a schematic illustration of the exteriormagnetic circuit. The coils of the suppressed core are then wound on theremaining cores, and the coil systems shown in Figs. 10 and 2 are thenwound in the manner shown in Figs. 11 and 12, respectively.

The manner in which a phase displacement of ninety degrees is obtainedbetween the fluxes of the shunt and series coils which is necessary toaccurate measurement in this type of meter can be more clearly describedby reference to Figs. 13 to 24. The core P in Fig. 13, which carries theshunt-winding, is provided with four polar projections A B B A,separated by an air-gap 6. Both halves A B and B A are symmetricallydisposed and wound in the same manner, so that it will be suflicient toexplain the diflerent windings and the production of the fluxes for onepair of pole-pieces A B. In order to produce the lead of themain-current field, the pole-pieces A and B carry primary windings,which are traversed by the main current, and secondary windingsshort-circuited in such a way that they produce in the pole-piece B aresulting flux which leads on the main or inducing current and which ismade to act upon the moving disk. The several arrangements of windingswhich may be wound upon the pole-pieces A and B may be divided into sixgroups, Fig. 14, which in the present case are intended as well for theprimary windings as for the secondary windings.

In Fig. 14 the kind of winding is shown on each pole-piece, so that thelength of the hatchings is proportional to the number of turns, and thedirection of said hatchings indicates in each case the sense of thewinding. The arrows under the figures show in magnitude and directionthe fluxes produced by the corresponding winding. The several figuresare diflerentiated in that in each case a determined number of turns isremoved from one of the polepieces and arranged upon the other. In Fig.14, for instance, two equal fluxes of opposite sense are produced. InFigs. 14 and 14 the flux increases in branch A and decreases in B, andit is hereby necessary, as in all the following figures, that a part ofthe produced fluxes be carried in an outer air branch. In Fig. 14 it iseven the whole sum of the fluxes produced in both branches which is socarried. The six groups may therefore be divided as follows: first,Figs. 14 and 14 two fluxes of different directions; second, Fig. 14,onlyone flux; third, Figs. 14, 14, and 14, fluxes of the same direction.

In order to obtain the necessary lead in the branch B, the followingrequirements must be met: first, that the two electromotive forcesresulting from the mutual induction between the main and secondary coilsin each of the two parts A and B of the secondary winding be of oppositesense; second, that the mutual induction between the two windings of Abe preponderant over the mutual induction between the two windings of B.Therefore the total electromotive force due to the mutual inductionbetween the primary and the secondary will be, according to the firstcondition, equal to the difference between the two partial electromotiveforces produced in branches A and B and said difference will be the sameas that induced in branch A, the phenomena being predominant in saidbranch according to the second condition. The first condition is metwith in the following manner: If the primary windings be of oppositesense upon A and B,"as in Figs. 14 and 14, the secondary windings mustbe of the same sense as in Figs. 14 and 14 and, vice versa, if theprimaries are of the same sense the secondaries must be of oppositesense. The second condition is met with by giving the coil A more turnsthan is given to B. This is obtained in all combinations:

j 14, 14, or 14 primary, 1 14 or 14 secondary,

14 14 or 14 primary,

14 or 14 secondary,

A having always more turns than B, or at least as many. The combinationof 14 with 14 must, however, be rejected, because the natural inductionphenomena are exactly balanced, so that the desired effect could not beobtained. Again, any combination employing 14 as a secondary is to berejected, because no secondary flux would traverse B where the resultingflux has to be brought in.

We will now demonstrate that when the above-mentioned conditions are metwith the desired lead of the flux is obtained in the branch B. Assuming,for instance, the combination of 14 as primary and 14 as secondary coil,which is the one shown in Fig. 13, in the vector diagram of Fig. 21, I1is the volume of the current in the primary coil and 7 1 the fluxproduced in the branch A by the primary coil, which flux by thewell-known equation is:

4 7T M I1 4 7r 77.2 11 RI and is negative, this branch being coiled inthe opposite sense. corresponding portion of the secondary winding, anelectromotive force 01, due to mutual induction, which force and is inquadrature with $1. $2 creates in the same way through the second branchof the secondary an electromotive force I d $2 n2 d t which is inopposition with @1, because $2 is opposed to $1 and smaller than 01,because n2 n1 and R inAand I I g -l-dc 127712 @2 in B, and thecomposition of said fluxes with $1 and $2 gives the resulting fluxes 1and /2 really existing in the branches A and B. These compositions areindicated by the diagrams of Figs. 21 and 21, which are derived from 21as regards the phase of i2 and of the fluxes $1 $2 $1 $'2 and which showthat the resulting flux 1 of A has a lag equal to an angle behind theinducing-flux $1, but that the resulting flux in B has a lead equal toan angle on the inducing-flux $2, the desired effect being thusobtained, The combinations of the windings 142 and 14 as primarywindings with 14 as the secondary one produce the same phenomena. Theyonly differ from the preceding combination in that $1 $2. The second ofthe required conditions is thus obtained even more fully. Again, thecombinations of the windings 14 or 14: as primaries with 14f assecondary satisfy the requirements, because @1 and 02 are always inopposition and e1 e2, $1 being greater than $2 and n1 being greater thanW2. Inversely, the combination of a winding such as 14 or 14 as primarywith a winding such as 14:, 1A", or 14 as secondary again fulfils therequire- This may be demonstrated as follows: Assuming that 14 be theprimary winding and 141 the secondary, Fig. 22, the primary fluxes $1and $2 produced in A and B are equal and of the same direction, becausem m $1 produces in' the corresponding part of the secondary anelectromotive force 01 due to mutual induction, which electromotiveforce $2 produces in the second branch of the secondary winding anelectromotive force;

in B. $2 is negative, the windings being of opposite sense. Theirrespective compositions with $1 and $2 (shown in Figs. 22 and 22") givethe resulting fluxes 1 and $2 really existing in branches A and B. 1lags behind $1 by an angle and 2 leads on $2 by an angle Thecombinations of 14 as a primary with 14: as a secondary, and of 1 1 as aprimary with 142 142 14? as a secondary give the same result, thedifference with the preceding case consisting in the greater differencebetween the values of 61 and e2.

As stated before, the branches A B B A, provided withthe'above-mentioned windings, are made to act upon the rotary disk, thefollowing advantages being obtained by the symmetrical disposition ofthe windings: First, the electromotive forces due to induction which maybe created between said windings and the shunt-windings are neutralized,and, second, all retarding or braking moments non-proportional to theenergy spent in the circuit, but produced by the current to be measured,are eliminated.

The diagram of Fig. 16 shows a form of execution in which only thebranches B B, in which the resulting flux is leading, are made to actupon the disk.

As shown in Figs. 17, 18, and 19, the four branches A B B A may also beunited, so as go form one group and act together upon the is z.

With a primary winding according to Figs.

14: or 142 and a secondary winding according 'to Figs. 14c or 141 thefluxes indicated in Fig.

$1 creates, through the l ments and gives a resultant flux leading in B.5

17 are created, and six couples of forces are thus obtained with theshunt flux 1 between A and B, one couple proportionalto................i 1 2 between A and B, one couple proportionalto................. Z 2between B and B, two couples proportional to P2 4 between B and A, onecouple proportional to P2 9 5 between B and A, one couple proportionaltoP1 The total couple is therefore proportional to K (4 P2 2 P1) Q5 In thesame way the four secondary fluxes produce with the fluxes 45 a totalcouple which is proportional to so that the resulting total couple is K(Z 'l' P 2 P li Q As before explained, the flux 2 has a lead on P2, andas 1 1 lags behind Z 1 so #1 has also a lead on $1 1, so that the sameresult is obtained as if the resulting couple were created by a fluxleading on the current volume, and the desired effect is therefore againsecured.

In the device of Fig. 18 the total of the six couples due to the primaryfluxes is and that of the six couples due to the secondary fluxes is K(4 P2 2 P1) The total resulting couple is thus In this case it isevident that the couple of forces is stronger, but the lead is smaller.

Figs. 23 and 24 show the diagrams corresponding to the windings of Figs.17 and 18, respectively.

In the device of Fig. 19 the primary winding is arranged according toFig. 14 and the secondary winding according to Figs. 14" and 14.

The vector diagram of Fig. 20 shows that in this case also a flux isobtained in branch B, which is in quadrature with the shunt flux. If Jbe the primary current and $1 the flux produced in branch A, thesecondary currentz' produces in branch B aflux P, leading on J by anangle fl, (or a flux 5 the lag of which is so that both fluxes are inquadrature with the shunt-flux.

The secondary winding of A B B A may in all forms of execution either beconnected in series or be short-circuited upon each two branches.

Figs. 25 to 29 show the coils as used in practice, and Figs. 30 and 31show a complete apparatus based on the above-stated princip es.

This apparatus is constructed in the following manner: A base C bearsfour arms K K and L L. The two first arms K K support a recording-clockmechanism H of any usual kind, which does not need to be here describedmore in detail. The two other arms L L support a horizontal plate Q,made of zinc or any other suitable non-magnetic material. On the base Cis fixed the shunt-electromagnet P, made of laminated iron, and on thebranches of which are wound two coils M M, traversed by theshunt-current. This electromagnet is divided at its middle plane by anair-gap c, Fig. 25, so as to form two broad poles. Said poles emit,through the extensions A B B A, fluxes rejoining the armature R. Saidarmature, which forms the magnetic circuits of the electromagnet, issupported by a plate Q in a slideway in which it is adapted to slideparallel to the extensions A B B A of the electromagnet. On saidextensions themselves are wound two systems of coils first, a primarycoil 1 2 3 4 5 6, Figs. 25 and 26, traversed by the main current andcomprising a coil embracing the four extensions A B B A and two coilswound in the same direc-- an adjustable resistance 1, Figs. 28 and 29,of

low self-induction, mounted in series with the shunt-coils M M. It isnecessary that the section of rings 7 8 and 9 10 should be somewhatlarger than required in order to give to the meter a lead in excess whena displacement occurs, which excess is corrected by rephasing theshunt-current with respect to the potential diflference by adjusting theresistance r. The addition of said resistance is advantageous in that ithas no influence on' the graduating of the meter withoutdisplacement,having a strong action upon the displacement of the shunt-currentwithout practically modifying the intensity thereof. A second movablepiece S may also be shifted on the horizontal plate Q and permits ofobtaining the necessary sensibility on starting and with small outputs,the lateral shifting of said piece producing a certain amount ofasymmetry in the fields of the electromagnet, which results in a smalltorque acting in opposite directions, according as S is near A B or A B.The plate Q carries also the permanent magnet E, securing theproportionality of the indications given by the instrument and themovable bearingV of the driving-shaft a. The upper end of said shaft issupported in a bracket m, Fig. 30, and said shaft, which drives theclock-gear (not shown) of. the recording mechanism H by means of worm0;,

formed thereupon, has fixed upon it a disk D, which passes through theair-gaps of the driving-electromagnets and of the permanent magnet E.

Shaft a is normally supported on a jewel in bearing V; but in order toprotect the pivot of shaft a and its jewel against jarring in shipmentthe bearing V may be removed and replaced in inverse position. It thenraises the shaft, and the disk D sticks against the magnet.

A casing F, made of ivorine or other suitable material and fixed to baseG, contains the terminals 0 Y) b I) 5 b, to which are respectivelyconnected the ends of the windings and of the conducting-wires.

That I claim, and desire to secure by Let.

ters Patent of the United States, is-

1. The combination with an alternating-current circuit, of means formeasuring the true energy therein, comprising a coilconnected in shunt,and a coil connected in series with said circuit having a secondary coilin inductive relation therewith and cooperating to produce a pluralityof dephased fluxes, and a rotating member arranged within the influenceof the shunt and series fluxes; substantially as described.

2. In a motor-meter for alternating currents, the combination of arotor, a series coil, a shunt-coil acting with the series coil, and ashort-circuited coil in inductive relation with the series coil, saidseries and short-circuited coils having their windings so disposed as tocause leading and lagging flux components with respect to the current;substantially as described.

3. In an electric meter, a shunt or potential coil, a series or currentcoil, and phase-adjusting means in inductive relation to saidcurrentcoil and cooperating therewith to produce a flux in advance ofthe main current; substantially as described.

4. In an electric meter, a shunt or potential coil, a series or currentcoil, phase-adjusting means in inductive relation to said currentcoiland cooperating therewith to produce a flux in advance of the maincurrent, and means for adjusting the phase of the current in theshunt-circuit; substantially as described.

5. In an electric meter, a shunt-coil, a series coil, phase-adjustingmeans in inductive relation to said series coil and cooperatingtherewith to produce a flux in'advance of the main current, and meansfor adjusting the time constant of the shunt-circuit; substantially asdescribed.

, 6. In an electric meter, a shunt-coil, a series coil, andphase-adjusting means in inductive relation to said series coil andcooperating therewith to produce a flux component displaced ninetydegrees from the flux of the shunt-coil; substantially as described.

7. In an electric meter, a shunt-coil producing a lagging flux, a seriescoil producing a flux substantially in phase with the current, and meansin inductive relation with said series coil for causing a flux inadvance of the current therein;- substantially as described.

8. In an electric meter, a shunt-coil producing a lagging flux, a seriescoil producing a flux substantially in phase with the current, and meansin inductive relation with said series coil for causing leading andlagging components of the flux due to the series coil; substantially asdescribed.

9. In an electric meter, a shunt-coil producing a lagging flux, a seriescoil producing a flux substantially in phase with the current, and meansin inductive relation with said coils for causing a further lag of theshunt-flux and a leading component in the series flux; sub stantially asdescribed.

10. In an electric meter, a shunt-coil producing a lagging flux, aseries coil producing a flux substantially in phase with the current,means in inductive relation with said coils for causing a further lag ofthe shunt-flux and means for adjusting the time constantof theshunt-circuit; substantially as described.

11. In an electric meter, the combination of a core provided with apotential coil, polar projections on said core, a current-coil carriedby said polar projections, and means also carried by said polarprojections for displacing the phase of flux therein due to thecurrent-coil; substantially as described.

12. In an electric meter, the combination of a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said slot orair-gap, a current-coil carried by said projections, andashort-circuited coil in inductive relation to said current-coil;substantially as described.

13. In an electric meter, the combination of a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said slot orair-gap, a current-coil carried by said projections, a short-circuitedcoil in inductive relation to said current-coil, an armature for saidcore, and a movable member disposed between said armature and core;substantially as described.

14:. In an electric meter, the combination of a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said slot orair-gap, a current-coilcarried by said projections, and a rotatingmember arranged within the influence of the resultant fluxes developedin said core and projections; substantially as described.

15. In an electric meter, the combination of a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said slot, acurrent-coil carried by said projections, and a secondary coil alsocarried by said projections in inductive relation with saidcurrent-coil; substantially as described.

16. In an electric meter, the combination of a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said slot, acurrent-coil carried by said projections, anda secondary coil ininductive relation with said current-coil arranged to modify the phaseof the flux due to the current-coil; substantially as described.

17. In an electric meter, a core having a plurality of polar projectionsdisposed on opposite sides of an air-gap, current and potential coilscarried by said core, and means for causing a phase displacement betweenthe fluxes traversing different projections on the same side of theair-gap; substantially as described.

18. In an electric meter, a core having a plurality of polar projectionsdisposed on opposite sides of an air-gap, current and potential coilscarried by said core, and means for causing a phase displacement betweenthe fluxes due to the current-coil traversing different projections onthe same side of the airgap: substantially as described.

19. In an electric meter, a core having a plurality of polar projectionsdisposed on opposite sides of an air-gap, current and potential coilscarried by said core, and a short-circuited coil on said projections forcausing a phase displacement between the fluxes traversing differentprojections on the same side of the air-gap; substantially as described.

20. In an electric meter, the combination with a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said air-gap, acurrent-coil on said polar projections having portions on either side ofthe air-gap unsymmetrically arranged, and a movable disk arranged withinthe influence of fluxes developed in said core; substantially asdescribed.

21. In an electric meter, the combination with a core provided with apotential coil, a slot or air-gap in the magnetic circuit of said core,polar projections located on said core on either side of said air-gap, acurrent-coil on said polar projections having a portion disposed aboutall of said polar projections and other portions disposed about singleprojections on either side of the air-gap, and a movable disk actuatedby said coils; substantially as described.

22. In an electric meter, a core provided with a potential coil andhaving a plurality of polar projections disposed on opposite sides of anair-gap, and a current-coil on said polar projections having similarportions oppositely arranged on either side of said air-gap, thewindings of the coil on the same side of the air-gap beingunsymmetrically arranged on the polar projections; substantially asdescribed.

23. In an electric meter, a core provided with a potential coil andhaving a plurality of polar projections disposed on opposite sides of anair-gap, a current-coil on said polar projections having similarportions oppositely arranged on either side of the air-gap, the windingsof the coil on the same side of the air-gap being unsymmetricallyarranged on the polar projections, and short circuited coils about thepolar projections on each side of the air-gap; substantially asdescribed.

24. In an electric meter, a core provided with a potential coilandhaving a plurality of polar projections disposed on opposite sides of anair-gap, and a current-coil on said polar projections having similarportions oppositely arranged on either side of the air-gap, the windingsof the coil on the same side of the air-gap having portions woundrespectively about all of the projections and about single projectionson that side; substantially as described.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

ALPHONSE JEAN FRAGER.

Witnesses:

LOUIS RnviM, AUGUSTUS E. INGRAM.

